What were the first organisms to have sex? We may never know the answer, but as Bill Nye explains in this Big Think interview, scientists are very interested in why sexual activity remains so popular in nature...

Why Are "Cougars" Multiplying? Where Is It the Norm for Men to Have Sex With Men?

We accept the evolutionary explanation as to why older men tend to seek younger, more fertile women; but recently there has been an increase in "cougars," older women pairing with younger men. How does that trend serve our species? In his Big Think interview, Ted Fischer ponders this and other mysteries of evolution, sex, and love.

He explains that love's purpose, at least historically, has been to ensure that we bear and raise children successfully. And while that human instinct is universal across cultures, how we form family bonds differs around the world. The men of the Sambia tribe of New Guinea establish intimate relationships with one another before becoming paired with a wife. And in modern Western society, emphasis on independent sexual attraction, rather than familial influence, instigates love. Like the village matchmakers of old, however, new algorithms used by Internet dating sites attempt to calculate successful pairings.